689WHP @ 40PSI
When news of the impending arrival of the EVO VIII hit the shores of America the tuning sector of the industry just about short circuited. The most euphoric of these celebrations was seen in the Diamond Star community where the market was shriveling like a grape in the sweltering desert sun. When Mitsubishi took the Eclipse "up market" and out of the tuner scene by going V6, Diamond Star tuners were left foaming at the mouth like ravenous pit bulls.
The EVO VIII brought about the triumphant return of the 4G63 turbocharged four-cylinder engine and DSM tuners had their savior. In fact, they had a leg up on the competition because the 4G was their baby ... their diamond in the rough (sorry). Further, they had in depth knowledge of drivetrain maladies and more importantly inroads to correcting these OE shortcomings. The pit bull had something to chew on...the tailpipes of unsuspecting WRXs.
One of these reinvigorated DSM tuners is Pruven Performance of Milford, Connecticut. Pruven and its prime mover, Dejan "Dan" Cokic, started the old fashioned way; with a car and a dream. Soon a hobby became a business and for Pruven the 4G63 was their rite of passage. Cokic made it to the top 13 fastest 2.0-liter Diamond Stars in the February 1999 issue of Turbo magazine.
Eventually his stripped down 1990 Eclipse GSX, which was painted orange with some "old school" flame graphics ran a 9.6 at 144 mph quarter mile without nitrous.
Fast forward to 2003 and Pruven was quick to acquire a Mitsubishi Lancer Evolution VIII. Initially, the car was bought for research and development and within the first week Pruven had the car running mid 12s.
After further experimenting, Cokic and his crew fabricated a turbo kit and went to the track with 480 hp at the wheels. The EVO produced an 11.1-second, 126-mph timeslip at full weight and full trim. All this with what Pruven calls, "a street turbo setup featuring a Forced Performance 3065 turbo."
Tuning can be a very Darwinistic exercise, natural selection, evolution and our favorite; natural progression. This usually means bigger, as in bigger turbos, bigger boost, bigger injectors and bigger tuning schemes. The unfortunate losers in this power play are the stock engine internals. Since Pruven was shooting for the moon the block was filled with the right stuff.
The 4G63's reciprocating mass is made up of Pruven-spec Arias pistons and Crower rods swinging on a strengthened stock crank. Basically, the same shortblock that Pruven would install in a customer car. The pistons are Silicon free, have different positioning of the ring lands than stock and the valve relief areas are significantly bigger. The slugs also feature heavy duty wrist pins compared to off-the-shelf units and a custom dish design. "These pistons took a few years to get perfect through many R&D sessions," says Cokic. "They could actually be called something like Version 7."
The block was O-ringed for improved sealing and topped with a reworked cylinder head. All porting and polishing was performed in-house at Pruven and the head has been fitted with 1mm oversized valves along with dual valve springs and titanium retainers. Valve actuation is handled by an eclectic HKS/JUN camshaft combination. "We have tried many, many combinations and found the combination of 280-degree HKS cams on the intake side and 272-degree JUN units on the exhaust side work the best for us. Seeing that we have the dyno at our disposal," says Cokic, "we have been able to test plenty of 4G63 cams over the years."